1. Field of the Invention
The present invention relates, in general, to safety related to towing vehicles such as towing and towed vehicles and the hitch, tow bar, or other connection as found in roller coasters and other rides in amusement parks and with use of trailers and other vehicles towed commercially and recreationally, and, more particularly, to devices for restraining mechanical components used to connect a drive or towing vehicle to a trailing or towed vehicle in the case of a failure of one or more of the components and, in some cases, for maintaining the towing connection or assembly between the two vehicles upon component failure (e.g., to retain the tensile connection between the vehicles to allow safe stopping of the vehicles for maintenance).
2. Relevant Background
Amusement and theme parks are popular entertainment destinations for people worldwide. Many people visit these parks for the excitement associated with roller coasters and other thrill rides. To continue to attract these visitors or guests, all rides including the thrill rides have to be designed, maintained, and operated at extremely high levels of safety. Even one accident per thousands upon thousands of rides is considered too many by park management as well as the general public, and accidents on these rides attract public attention.
Statistically, roller coasters and other amusement park rides are very safe with guests generally having a higher risk of injury driving to the park than on the park's roller coasters. To this end, roller coasters and other thrill rides are designed with many safety systems such as mechanical fail-safe devices such as redundant structural components to protect against the failure of a single component. For example, roller coasters and other rides involve vehicles that are connected in trains or in two or more sets of vehicles or cars such that there is a towing vehicle and a towed, trailing vehicle. The towing assembly for a typical roller coaster may include a rigid tow bar extending between the two vehicles and connected at each end with a coupling assembly (or hitch assembly). To reduce risks associated with failure of the tow bar or coupling assemblies, a safety cable is typically provided that is attached to each vehicle and is designed to take the load in the tensile direction in the event of a failure. During operation, if the primary towing assembly fails the safety cable stretches and keeps the towed vehicle with the towing vehicle. Unfortunately, the cable is only useful in tension and when the towing or lead vehicle brakes to a stop the towed vehicle often will collide into the back of the towing vehicle. In some cases, a redundant load path is provided in the form of a secondary tow bar and the two tow bars may share the load. However, this increases the complexity of the ride design and increases manufacturing and maintenance costs associated with the roller coaster or other park ride.
Another safety concern associated with towing assemblies and existing safety devices is that failure of components may result in broken parts separating from the assembly. A broken bolt, pin, tow bar component, or other part may become a projectile as it is released from the fast moving vehicle. The towing and towed vehicles may also be on a track high above the ground when the failure occurs and the broken part or pieces may fall on park guests. Either of these failure scenarios may result in injury of park visitors that are not even on the ride. The failure to restrain the broken parts may also result in a tow bar or other part becoming disconnected at one end and dropping downward toward the track or rail. If the back end (or end near the towed vehicle) falls downward, the tow bar may simply be dragged, but if the front end (or end near the towing vehicle) falls downward, the tow bar may catch on the ground, the track or rail, or other structure. Since the vehicle may still be moving at high speed, the dropped or dangling tow bar may lift the towed vehicle off the ground causing a crash (e.g., similar to a track and field participant in the pole vault event).
Towing safety is a concern in many other areas besides with towed vehicles at amusement parks. In the United States, more and more people are using their primary vehicle, such as a sports utility vehicle, a pickup truck, or other automobile, to tow other vehicles such as trailers carrying recreational equipment or camping trailers. The recreational vehicle (RV) industry is rapidly expanding, too, with many drivers attaching trailers or other vehicles behind their RVs with a towing assembly. In commercial settings, the roads are filled with semis and other trucks pulling trailers that are attached with tow bars, hitches, and other towing assemblies. Failure of the components of these towing assemblies may result in projectiles being sent bouncing down the highway because, if a safety device is used, it typically will only be a chain or wire cable used to try to retain the trailer with the towing vehicle (e.g., to function under tensile load to pull the towed vehicle until the driver can pull off the road). The use of a safety chain, though, may result in the towing assembly or tow bar falling down, and the front of the tow bar may dig into or catch on a physical structure causing the trailer to vault off the ground or to over turn causing a serious accident. Also, the safety chain is ineffective under compressive loading and will provide no protection from the trailing or towed vehicle colliding with the lead or towing vehicle when that vehicle comes to a stop (e.g., the trailing vehicle has no brakes and its momentum will cause it to continue to roll into the braking lead vehicle).
Hence, there remains a need for an improved safety device for use with towing assemblies such as tow bars, hitches, and the like. Preferably, such a safety device would be easy to install, relatively inexpensive to manufacture and maintain, and protect against broken components breaking away and becoming dangerous projectiles.